1. Field of the Invention
The present invention relates to logic systems to be connected between two digital systems capable of exchanging items of information so as to provide a coupling of such logic systems, taking into account the characteristics of the signals liable to be exchanged and the chronology proper to each one of the digital systems and their relative chronology.
2. Description of the Prior Art
Interface logic circuits achieving for example the coupling between a computer and a peripheral (such as a printer, a control unit of a flexible disc or the like) are known in the prior art.
These logic circuits, designed case by case by solving the problems of coupling between the different elements of a processing system, are commonly designated by the term "couplers".
Independently of the adaptation of the levels of the electric signals liable to be exchanged, which adaptation does not come within the scope of the present invention, the general functions of such a coupler may be:
Conversions of the formats of the exchanged data; PA1 The checkings carried out of these data; PA1 The control of the duration of the data signals and the control signals so that they are in accordance with the requirements of duration imposed by the system which must receive them.
To carry out these functions, the coupler must be capable of processing a disparate collection of exchange signals. It will consequently have to have available "resources" which enable it to recognize an electric level, to reply to a demand, to emit a demand, to detect signal transitions, to measure a duration, or to calibrate a waveform. Generally, these different types of processings are effected by different adapted circuits connecting the outputs of one of the digital systems to the corresponding inputs of the other, the assembly of these circuits forming the coupler.
Presently known couplers do not integrate all of the functions mentioned hereinbefore in the same circuit.